TWI881271B - Light sensing element and manufacturing method thereof - Google Patents

Abstract

The present invention provides a manufacturing method of a light sensing element. The method includes the following steps: providing a preformed structure, wherein the preformed structure includes a semiconductor structure and a band pass filter layer stacked on the semiconductor structure; performing a laser cutting process on the preformed structure along a direction perpendicular to a surface of the band pass filter layer, so that the preformed structure is cut into a plurality of light sensing elements. Each light sensing element has a plurality of side walls. Wherein each side wall forms a scorched surface by the laser cutting process to block the entry of external light.

Description

Light sensing element and manufacturing method thereof

The present invention relates to a photosensitive element and a manufacturing method thereof, and in particular to a photosensitive element and a manufacturing method thereof which can effectively reduce noise.

It is known that a photosensitive element will limit the passage of light with a specific wavelength band by setting a band pass filter (BPF) film layer on the light-collecting surface to provide a sensing function for the specific light; at the same time, the band pass filter film layer will reflect the light outside the specific wavelength band to limit its entry into the light absorption layer of the photosensitive element, thereby reducing the generation of unnecessary noise.

Before the photosensitive element is formed, a cutting operation is performed on the photosensitive structure to be formed to obtain the photosensitive element of the required size. However, the current cutting operation mostly uses diamond cutting, so that the sidewalls formed by the photosensitive element after cutting become light-transmissive surfaces. Since there is no BPF film layer on the surface of these sidewalls, once light enters the interior of the element from any sidewall surface, it will cause the light outside the specific wavelength band to be absorbed by the light absorption layer, resulting in the generation of noise. In this way, the sensing accuracy and/or performance of the photosensitive element will be affected.

Therefore, how to design a light sensing element and its manufacturing method to improve the above-mentioned problems and suppress the generation of noise is indeed a topic worthy of research.

The purpose of the present invention is to provide a method for manufacturing a light sensing element that can effectively reduce noise.

Another object of the present invention is to provide a light sensing element manufactured by the aforementioned manufacturing method.

To achieve the above-mentioned purpose, the manufacturing method of the photosensitive element of the present invention includes the following steps: providing a structure to be formed, wherein the structure to be formed includes a semiconductor structure and a bandpass filter layer stacked on the semiconductor structure; and performing at least one laser cutting process on the structure to be formed along a direction perpendicular to the surface of the bandpass filter layer to cut the structure to be formed into a plurality of photosensitive elements, each of which has a plurality of side walls; wherein each side wall is formed into a scorched surface by at least one laser cutting process to block the entry of external light.

In one embodiment of the present invention, the carbonized surface is composed of carbide.

In one embodiment of the present invention, the carbon content of the charred surface is not less than 5%, and the oxygen content of the charred surface is not less than 5%.

In one embodiment of the present invention, the scorched surface covers at least the side surfaces of the semiconductor structure.

In one embodiment of the present invention, the semiconductor structure is made of III-V semiconductor materials.

In one embodiment of the present invention, the semiconductor structure is composed of a compound semiconductor of indium phosphide and gallium indium arsenide.

In one embodiment of the present invention, at least one laser cutting process includes a first laser cutting process, a second laser cutting process and a third laser cutting process, and the output power of the laser used in the first laser cutting process is 0.2-1W, the reference frequency is 10-18kHz, and the moving speed is 30-70mm/s.

In one embodiment of the present invention, the output power of the laser used in the second laser cutting process and the third laser cutting process is 1-5W, the reference frequency is 8-13kHz, and the moving speed is 100-180mm/s.

The present invention also includes a photosensitive element manufactured using the above manufacturing method, the photosensitive element includes a plurality of side walls, a semiconductor structure and a bandpass filter layer. Each of the side walls forms a scorched surface to block the entry of external light. The semiconductor structure includes a light absorption layer. The bandpass filter layer is stacked on the semiconductor structure.

In one embodiment of the present invention, the bandpass filter layer is formed by stacking 1520 sets of hydrogen silicide material layers and silicon dioxide material layers.

Accordingly, the present invention cuts the light sensing element into shape through a laser cutting process, and forms a scorched surface on each side wall of the light sensing element to prevent external light from entering the light absorption layer in the light sensing element from the side wall, so that the light sensing element can reduce the generation of noise.

Since the various aspects and embodiments are only exemplary and non-restrictive, after reading this specification, a person with ordinary knowledge may also have other aspects and embodiments without departing from the scope of the invention. According to the following detailed description and patent application scope, the features and advantages of these embodiments will be more prominent.

In this document, "a" or "an" is used to describe the elements and components described herein. This is only for convenience of explanation and to provide a general meaning for the scope of the present invention. Therefore, unless it is obvious that it is otherwise intended, such description should be understood to include one or at least one, and the singular also includes the plural.

In this article, the terms "first" or "second" and similar ordinal numbers are mainly used to distinguish or refer to the same or similar elements or structures, and do not necessarily imply the order of these elements or structures in space or time. It should be understood that in some cases or configurations, ordinal numbers can be used interchangeably without affecting the implementation of the present invention.

As used herein, the terms "include," "have," or any other similar terms are intended to cover a non-exclusive inclusion. For example, a component or structure having plural elements is not limited to those elements listed herein but may include other elements that are not expressly listed but are generally inherent to the component or structure.

Please refer to FIG. 1 and FIG. 2 together, where FIG. 1 is a flow chart of the manufacturing method of the light sensing element of the present invention, and FIG. 2 is a schematic diagram of the structural process of FIG. 1. As shown in FIG. 1 and FIG. 2, the manufacturing method of the light sensing element of the present invention includes the following steps:

Step S1: providing a structure to be formed, wherein the structure to be formed includes a semiconductor structure and a bandpass filter layer stacked on the semiconductor structure.

First, the present invention forms a structure 200 to be formed of a light sensing element by a semiconductor process, so as to provide the structure 200 to be formed for subsequent processing steps. The structure 200 to be formed includes at least a semiconductor structure 210 and a bandpass filter layer 220 stacked on the semiconductor structure 210. The semiconductor structure 210 is mainly a multi-layer structure formed by stacking semiconductor materials through an epitaxial process. In one embodiment of the present invention, the semiconductor structure 210 is made of III-V semiconductor materials, wherein each layer of the structure can adopt a combination of different III-V semiconductor materials, and selectively doped with specific elements according to design requirements to form semiconductor material layers with different characteristics, but the present invention is not limited to this. The semiconductor structure 210 includes a light absorbing layer 211, which is used to absorb light entering the structure. In addition, the semiconductor structure 210 may also include a layered structure formed by other materials through corresponding processes, such as an electrode layer, an insulating layer, an anti-reflection layer, etc.

The bandpass filter layer 220 is generally stacked on the semiconductor structure 210. The bandpass filter layer 220 is mainly used to limit the passage of light in a single or multiple specific bands, and to block the passage of light outside the aforementioned specific bands (such as the so-called cut-off band). The bandpass filter layer 220 is a multi-layer structure stacked by a coating process with a transparent material. Each layer structure can use a combination of different materials, so that the bandpass filter layer 220 can form the characteristics of light in specific bands of different ranges according to design requirements, and block the passage of light in different bands. For example, in one embodiment of the present invention, the bandpass filter layer 220 includes a plurality of layered structures, wherein the plurality of layered structures are formed by stacking 15-20 groups of hydrogen silicide material layers and silicon dioxide material layers; that is, the bandpass filter layer 220 is composed of a layer of hydrogen silicide material layer and a silicon dioxide material layer as one group, and the bandpass filter layer 220 is formed after 15-20 groups are stacked successively, but the number of layers and material selection of the bandpass filter layer 220 are not limited to the aforementioned contents.

Step S2: performing at least one laser cutting process on the structure to be formed along a direction perpendicular to the surface of the bandpass filter layer to cut the structure to be formed into a plurality of light sensing elements; wherein each light sensing element has a plurality of side walls, and each side wall is formed into a scorched surface by the laser cutting process to block the entry of external light.

After providing the structure 200 to be formed in the aforementioned step S1, the present invention can then perform at least one laser cutting process on the structure 200 to be formed along a direction perpendicular to the surface 221 of the bandpass filter layer 220 to cut the structure 200 to be formed into a plurality of photosensitive elements 1; that is, each photosensitive element 1 includes a portion of the aforementioned semiconductor structure 210 and a portion of the bandpass filter layer 220. Each photosensitive element 1 after cutting and forming has a plurality of side walls. For example, the photosensitive element 1 after cutting is generally a rectangular body, so the photosensitive element 1 has four side walls. The size of each photosensitive element 1 can be changed according to different design requirements.

Since the laser cutting process uses a high-energy focused laser to perform a cutting operation on the structure 200 to be formed, during the cutting and forming process of the plurality of light sensing elements 1, the high-energy laser causes the side walls of each light sensing element 1 to sinter and form a scorched surface. The scorched surface is a rough surface, and the scorched surface is mainly composed of carbides. In other words, a carbide layer can be formed on each side wall of each light sensing element 1, and the carbide layer can absorb the light irradiated to the side wall, thereby providing an effect of blocking the entry of external light.

In one embodiment of the present invention, at least one laser cutting process may include a first laser cutting process, a second laser cutting process, and a third laser cutting process performed sequentially. The output power of the laser used in the first laser cutting process is 0.2-1W, the reference frequency is 10-18kHz, and the moving speed is 30-70mm/s; the output power of the laser used in the second laser cutting process and the third laser cutting process is 1-5W, the reference frequency is 8-13kHz, and the moving speed is 100-180mm/s. The lasers selected for the laser cutting processes provide sufficient output power, reference frequency and moving speed during cutting, so that the side walls of each photosensitive element 1 cut and formed can form a scorched surface, but the selected laser parameters and the number of executions of the laser cutting process are not limited to this.

Please refer to FIG3 for a schematic diagram of the structure of an embodiment of the photosensitive element of the present invention. The photosensitive element of the present invention is manufactured by the aforementioned method for manufacturing the photosensitive element. The structure of the photosensitive element of the present invention is further described below. As shown in FIG3, in the present embodiment, the photosensitive element 1 of the present invention at least includes a plurality of side walls A, a semiconductor structure 10 and a bandpass filter layer 20. The semiconductor structure 10 is the basic structural component of the photodiode structure 1 of the present invention. The semiconductor structure 10 can be roughly divided into a substrate 11, a first semiconductor layer 12, a light absorption layer 13 and a second semiconductor layer 14. The substrate 11 is mainly made of indium phosphide (InP) material. The first semiconductor layer 12 is mainly made of silicon-doped indium phosphide (InP) material. The light absorption layer 13 is mainly made of undoped indium gallium arsenide (InGaAs) material. The second semiconductor layer 14 is mainly made of silicon-doped indium phosphide material. The semiconductor structure 10 can form a first electrode 30 on the other side of the substrate 11, and the first electrode 30 is mainly made of an alloy material containing gold (Au).

A protective layer 40, an anti-reflection layer 50 and a second electrode 60 may be further included between the semiconductor structure 10 and the bandpass filter layer 20. The protective layer 40 is formed on the other side surface of the second semiconductor layer 14 of the semiconductor structure 10, and the protective layer 40 is mainly made of silicon oxide (SiO _x ) material. The anti-reflection layer 50 is formed on the protective layer 40 and the other side surface of the second semiconductor layer 14 of the semiconductor structure 10, and the anti-reflection layer 50 is mainly made of silicon nitride (SiN) material. The second electrode 60 maintains ohmic contact with the second semiconductor layer 14 of the semiconductor structure 10, and the second electrode 60 is mainly made of a gold-containing material. The bandpass filter layer 20 is formed on the anti-reflection layer 50 and the second electrode 60.

When the light sensing element 1 of the present invention is cut and shaped by the laser cutting process, a plurality of side walls A are generated, and a scorched surface A1 is formed on each side wall A by a high-energy focused laser. In this embodiment, the scorched surface A1 at least covers the side surface of the semiconductor structure 10, that is, the scorched surface A1 is formed on the side surface of the structure made of III-V semiconductor material. In one embodiment of the present invention, the carbon content of the scorched surface A1 is not less than 5%, and the oxygen content of the scorched surface A1 is not less than 5%, so that the scorched surface A1 is sufficient to present a non-light-transmitting state.

Accordingly, the light irradiated to the photosensitive element 1 of the present invention can only enter the light absorption layer 13 of the semiconductor structure 10 through the bandpass filter layer 20, so that the light received by the light absorption layer 13 is generally within a specific wavelength band; and the photosensitive element 1 of the present invention can effectively reduce the possibility of light of other wavelength bands entering the light absorption layer 13 from the side wall A through the formation of the scorched surface A1, thereby reducing the generation of noise.

Please refer to FIG4 for the noise rate test results of the conventional photosensitive element and the photosensitive element of the present invention. In the following experiments, the photosensitive element is a photosensitive element with a bandpass filter as an example, and the photosensitive element formed by the conventional saw cutting process is used as the control group R1, and the photosensitive element formed by the laser cutting process of the present invention is used as the experimental group R2, and the noise rates of the two after the test are compared. The upper part of Figure 4 shows the spectral characteristic diagram corresponding to the bandpass filter, wherein the first bandpass wavelength range that the bandpass filter of the photo sensor allows to pass is 1000-1150nm and the second bandpass wavelength range that can pass is 1350-1600nm, and the corresponding cut-off wavelength range of the bandpass filter is 1180-1350nm. The lower part of Figure 4 shows the actual spectral characteristic diagram corresponding to the aforementioned control group R1 and experimental group R2. The average noise rate presented by the control group R1 in the aforementioned cut-off wavelength range is greater than 10%, while the average noise rate presented by the experimental group R2 in the aforementioned cut-off wavelength range is less than 5%. It can be seen that, compared with the conventional photo sensor manufactured by the saw cutting method, the photo sensor manufactured by the manufacturing method of the present invention can obviously provide a lower average noise rate and can more effectively reduce the generation of noise.

The above embodiments are essentially only for auxiliary explanation, and are not intended to limit the embodiments of the application subject matter or the application or use of such embodiments. In addition, although at least one exemplary embodiment has been proposed in the aforementioned embodiments, it should be understood that the present invention can still exist in a large number of variations. It should also be understood that the embodiments described herein are not intended to limit the scope, use or configuration of the claimed application subject matter in any way. On the contrary, the aforementioned embodiments will provide a simple guide for those with ordinary knowledge in the field to implement one or more of the embodiments described. Furthermore, various changes can be made to the function and arrangement of the components without departing from the scope defined by the scope of the patent application, and the scope of the patent application includes known equivalents and all foreseeable equivalents at the time of filing the present patent application.

1: Photosensitive element 10: Semiconductor structure 11: Substrate 12: First semiconductor layer 13: Light absorption layer 14: Second semiconductor layer 20: Bandpass filter layer 30: First electrode 40: Protective layer 50: Anti-reflection layer 60: Second electrode 200: Structural part to be formed 210: Semiconductor structure 211: Light absorption layer 220: Bandpass filter layer 221: Surface A: Sidewall A1: Scorched surface R1: Control group R2: Experimental group S1~S2: Steps

FIG1 is a flow chart of the manufacturing method of the photosensitive element of the present invention. FIG2 is a schematic diagram of the structural process in conjunction with FIG1. FIG3 is a schematic diagram of the structure of an embodiment of the photosensitive element of the present invention. FIG4 is a diagram of the actual spectral characteristics of the known photosensitive element and the photosensitive element of the present invention.

S1~S2: Steps

Claims (10)

A method for manufacturing a photosensitive element, the method comprising the following steps: Providing a structure to be formed, wherein the structure to be formed comprises a semiconductor structure and a bandpass filter layer stacked on the semiconductor structure; and Performing at least one laser cutting process on the structure to be formed in a direction perpendicular to the surface of the bandpass filter layer to cut the structure to be formed into a plurality of photosensitive elements; Each of the photosensitive elements has a plurality of side walls, and each of the side walls is formed into a scorched surface by the at least one laser cutting process to block the entry of external light. A manufacturing method as described in claim 1, wherein the charred surface is composed of carbide. A manufacturing method as described in claim 1, wherein the carbon content of the charred surface is not less than 5%, and the oxygen content of the charred surface is not less than 5%. A manufacturing method as described in claim 1, wherein the scorched surface covers at least the side surface of the semiconductor structure. A manufacturing method as described in claim 1, wherein the semiconductor structure is made of Group III-V semiconductor materials. A manufacturing method as described in claim 5, wherein the semiconductor structure is composed of a compound semiconductor of indium phosphide and gallium indium arsenide. A manufacturing method as described in claim 1, wherein the at least one laser cutting process includes a first laser cutting process, a second laser cutting process and a third laser cutting process, and the output power of the laser used in the first laser cutting process is 0.2-1W, the reference frequency is 10-18kHz, and the moving speed is 30-70mm/s. A manufacturing method as described in claim 7, wherein the output power of the laser used in the second laser cutting process and the third laser cutting process is 1-5W, the reference frequency is 8-13kHz, and the moving speed is 100-180mm/s. A photosensitive element manufactured using the manufacturing method described in any one of claims 1 to 8, the photosensitive element comprising: a plurality of side walls, each of which forms a scorched surface to block the entry of external light; a semiconductor structure including a light absorbing layer; and a bandpass filter layer stacked on the semiconductor structure. The light sensing element as described in claim 9, wherein the bandpass filter layer is formed by stacking 15-20 sets of hydrogen silicide material layers and silicon dioxide material layers.